You can lose a lot of money with gambling, I lost around the 2 bitcoins with gambling on different gambling websites.
Of course this is logical you cannot always win but I still regret today that I invested so much for me in the online casino's.
Well you regret because you had losted but if you had won 4 btc with those 2 btc invested would you regret,for sure no,the thing is we cant win always ,its like play lotery,knowing that casinos has a better odds to win then lotery,but well in the end all had been made to be profitable otherwise wouldnt exist soo many casinos.